This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. BACKGROUND: The CINRG Quantitative Measurement System (CQMS) is a tool used to assess gross motor function, muscle strength, and pulmonary strength. It has been validated in Duchenne muscular dystrophy. It is the primary outcome tool used in the Cooperative International Neuromuscular Research Group (CINRG). In order to maintain high testing standards between all clinical evaluators in this multi-center group, reliability must be exhibited between newly trained evaluators as well as maintenance of testing standards among seasoned evaluators. Maintaining test reliability ensures that test data form multiple evaluators may be pooled for statistical analysis. PURPOSE: Assess the reproducibility of measures collected in Cooperative International Neuromuscular Research Group (CINRG) trials for neuromuscular disorders and to learn more about the relationship of those measures. Consistent training of the tester and reliability testing helps ensure testing standards are consistent among all clinical evaluators (CE) within the group. As a result, CINRG performs both structured new tester training with the CINRG gold standard CE then performs reliability testing with an already certified CE(s) every two years. The proposed study provides structured testing where the CINRG Gold Standard CE can visit the site and perform new staff training on local patients, and provides for the collected data to be available for analyses. Both the initial and reliability training involves is for a one to two day test session of clinical reliability of a CE at a given CINRG site between sites CE or as compared to the gold standard clinical evaluators of the CINRG multicenter group. DESIGN: In this study participants will be tested twice by both the CINRG Gold Standard CE and new CE. The variability of the measures will be examined. No treatment will be given and no invasive procedures will be performed.